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Chemistry GCSE > crude oils and fuels > Flashcards

crude oils and fuels Flashcards

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1
Q

what is crude oil a mixture of

A

hydrocarbons

compounds that only contain hydrogen and carbon - joined together by covalent bonds

most are alkanes

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2
Q

what is the general formulae for the family of alkane hydrocarbons

A

C(n)H(2n+2)

eg methane = CH(4)
ethane = C(2)H(6)

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3
Q

draw methane as an alkane molecule displayed formulae

A 
H
        |
H--C--H
        |
       H

covalent bonds =straight line
atom is shown as its symbol

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4
Q

name the alkanes in order of smallest to biggest

A 
methane
ethane
propane
butane
pentane 
hexane
octane
montane
decade
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5
Q

what type of hydrocarbons are alkanes

A

saturated hydrocarbons

means contain as many hydrogen atoms as possible in each molecule

no more hydrogen atoms can be added

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6
Q

what’s a saturated hydrocarbon

A

carbon atoms are joined together by single bonds

makes them unreactive
apart from boring or combustion which is their reaction with oxygen in the air

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7
Q

what is distillation

A

process used to separate pure liquid from a mixture of liquids

works when liquids have different boiling points

heats(evaporates)> cools (condenses)

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8
Q

how is fractional distilation different to normal distillation

A

different from distilation cause it separates mixture into different parts called fractions

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9
Q

how does fractional distillation work

A
  1. crude oil is heated to evaporate
  2. crude oil fed at bottom of a tall Column as hot vapour
  3. hot at bottom cool at top, several condensers coming off at different heights
  4. gases condense when they reach their boiling points
  5. different fractions are collected as different liquids at different levels

boils/condenses at different temperatures cause of different sizes of molecules

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10
Q

what has the lowest boiling points

A

Petrol , refinery gas (shorter carbon atoms)

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11
Q

what has the highest boiling points

A

bitumen, oil (longer carbon atoms)

cool to form very thick liquids or solids at room temperature

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12
Q

what are properties of short chain alkanes

A

low boiling point

less viscous( more runny)

more volatile(more likely to turn into a gas)

more flammable (easier it burns)

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13
Q

what are the properties of long chain alkanes

A

high boiling point

more viscous( less runny)

less volatile(less likely to turn into a gas)

less flammable (harder it burns)

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14
Q

where is crude oil derived from

A

biomass found in rocks, over millions of years

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15
Q

what comes out of the bottoms of fractional distillation Collums

A

residue

very thick, mixture of long-chain hydrocarbons, used in making roads and flat roof

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16
Q

what happens when the fractions have been collected

A

they need more processing before they can be used

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17
Q

are the long chain atoms near the bottom of the top in fractional distillation

A

substances with higher boiling points (long chain) condense at bottom and lower boiling points (short chain) condense at least he top

each fraction contains hydrocarbon molecules with a similar number of carbon atoms

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18
Q

what are lighter fractions used for and why?

A

used a fuels

because when they burn in plenty of air they release energy

called oxidised (meaning adding oxygen in a chemical reaction in which the oxides are formed)

propane+ oxygen > carbon dioxide+ water

19
Q

how can we test that carbon Dixie is produced in combustion

A

limewater goes cloudy

20
Q

how can you tell that water is produced in combustion

A

blue colbalt paper goes from blue to pink

21
Q

how is selfie dioxide produced

A

impurities containing sulphur is a product of fuels being burnt as fuels.

sulphur reacts with oxygen when we burn the fuel- creating sulphur dioxide

22
Q

what is sulphur dioxide and what does it do

A

poisonous gas

acidic

causes acid rain

can cause engine corrosion

23
Q

what is incomplete combustion and when does it happen

A

when there isn’t enough oxygen

instead of carbon dioxide being produced carbon monoxide is produced

24
Q

why is carbon monoxide poisonous

A

red blood cells pick it up and carry it around the blood instead of oxygen

even small amounts of carbon monoxide can be bad for you

25
Q

how are nitrogen oxides formed

A

high temperatures in an engine allow nitrogen and oxygen to form nitrogen oxides.

26
Q

what is nitrogen oxide

A

poisonous

can trigger asthma attacks

cause acidic rain

27
Q

what is particulates

A

tiny solid particles containing carbon and Unburnt hydrocarbons

get carried into the air

scientists think they damage our lungs and might cause cancer

28
Q

how are particulates produced

A

in Diesel engines

hydrocarbons are burnt with much bigger molecules

big molecules react with oxygen and don’t always burn completely - particulates are produced

29
Q

what does carbon dioxide do

A

main greenhouse gas in the air

absorbs energy released as radiation from surface of the earth

causes global warming, increased world’s temperature.

30
Q

what do particulates do

A

tiny solid particles made from carbon and Unburnt hydrocarbons

travel into the upper atmosphere, reflecting sunlight back into space- causing global dimming

31
Q

what does carbon monoxide do

A

affects the amount of oxygen that our blood is able to carry

particularly serious for people who have heart problems

32
Q

what does sulfur and nitrogen oxides do

A

make people suffer from asthma because of increased air pollution

cause acid rain because they dissolve in water droplets in the atmosphere
and react with oxygen creating sulphuric and nitric acids

rain with a low oh can damage plants and animals

33
Q

what’s a catalytic converter

A

catalytic converters in car exhausts- reduces carbon monoxide and nitrogen oxides produced

expensive because they contain precious metal catalysts- but are very effective

do not help reduce levels of carbon dioxide

34
Q

how do catalytic converters work

A

metal catalysts arranged so they have a large surface area

causes carbon monoxide and nitrogen oxides to react together and produce nitrogen and carbon dioxide

carbon monoxide + nitrogen oxide> carbon dioxide + nitrogen

35
Q

what do filters do

A

remove most particulates from the modern diesel engines.

the filets need to burn off trapped solid particulates otherwise they will get blocked

36
Q

how is sulfur dioxide removed in power stations

A

removed from flue (waste) gases by reacting it with calcium oxide or calcium hydroxide.

sulfur é impurities can also be removed from fuel before the fuel is burned (happens in cars and factories)

37
Q

so have can you reduce the effects of burning fuel

A
  1. catalyst converters
  2. filters
  3. reacting sulphur with calcium oxide/calcium hydroxide
  4. removing sulphur from fuel before burning fuel
38
Q

what’s a biofuel

A

fuels made from plant or animal products

39
Q

what’s a biodiesel

A

fuel for cars made from plant oils

40
Q

what are the advantages of biodiesel a

A
  1. cheaper than petrol and diesel - crude oil price going up
  2. carbon neutral
  3. it’s renewable and reliable
  4. makes other useful producers eh high energy food for goes and soap
41
Q

what does carbon neutral mean

A

the amount of carbon dioxide given off when it burns is balanced by the amount absorbed as plants it is made from grow

42
Q

What are the disadvantages of biodiesels

A
  1. freezes before traditional diesels and can turn into sticky goo at high temperatures in a engine
  2. can destroy habitats- large areas of tropic forest are being cut down and turned into Palm oil plantations for biodiesel- orangutans habitats destroyed
  3. used late areas of farmland where food could be produces. food becomes too expensive in poorer countries and people die
43
Q

what happens in complete combustion with hydrocarbons

A

the carbon in the hydrocarbons oxidises to carbon dioxide

the hydrogen oxidises to water

but needs to be plenty of air!!

44
Q

what is exothermic

A

a type of energy that releases energy from a fuel

Chemistry GCSE (12 decks)

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